This invention relates to a novel silicon-containing antimicrobial polymer composition and to a method of creating a solvent-free formulation of such polymeric antimicrobial material, preferably in the form of a dry powder or in solution in a solvent in order to impart antimicrobial activity unto or in another material. The antimicrobial polymer has superior antimicrobial properties compared to the similar monomer.
More particularly, this invention relates to a novel way to form an antimicrobial material that can be incorporated in or bound to a substrate such that it has a non-leaching antimicrobial property that is not dependent on the mechanism of leaching antimicrobial agents. The method described herein may be used to prepare or treat biocompatible devices or other products and impart antimicrobial properties to substrates containing the antimicrobial agent throughout the polymeric substrates. Additionally, the method described herein may be used to prepare or treat biocompatible devices or other products and impart antimicrobial properties to polymeric substrates containing the antimicrobial agent bound to the surface of the polymeric substrates. Further, the method described herein may be used to prepare liquid solutions with antimicrobial properties.
There has been a great deal of attention in recent years given to the hazards of bacterial contamination from potential everyday exposure. Noteworthy examples of such concerns include the fatal consequences of food poisoning due to certain strains of Eschericia coli being found within undercooked beef in fast food restaurants; Salmonella contamination causing sicknesses from undercooked and unwashed poultry food products; and illnesses and skin infections attributed to Staphylococcus aureus, Klebsiella pneumoniae, yeast, and other unicellular organisms. With such an increased consumer interest in this area, manufacturers have begun introducing antimicrobial agents within various everyday products and articles. For instance, certain brands of polypropylene cutting boards, liquid soaps, etc., all contain antimicrobial compounds.
Silicon-containing quaternary ammonium antimicrobial agents belong to a general class of antimicrobial agents termed cationic antimicrobial agents. This invention relates to a solvent-free polymer composition and to a method of creating a polymeric silicon-containing quaternary ammonium antimicrobial agent that is more effective than the monomeric form in solutions. As used herein, an “antimicrobial agent” is an agent that destroys or inhibits the growth of microorganisms, and particularly pathogenic microorganisms. The major classes of microorganisms are bacteria, fungi including mold and mildew, yeasts, and algae. Microorganisms can be found in the air, the water, in and on the human body and bodies of animals, soil, wastes, and on all surfaces. The microorganisms are deposited from the air, food and drink spills, dust, and dirt and tracked in soil, and from human and animal excreta such as sweat, urine, and feces. Organisms grow and multiply when there is available a nutrient source of food such as organic or inorganic material contained in such wastes, dirt, dust, and living tissue. For growth and multiplication, most microorganisms also require warm temperatures, and moisture. When these conditions exist, microorganisms multiply, grow and flourish. Microbial growth, however, leads to many problems, such as unpleasant odors ranging from stale to musty and mildew-like, to putrid and foul smelling, resembling ammonia. The growths also produce unsightly stains, discoloration, and deterioration of many surfaces and materials in which they come into contact. A more serious disadvantage of microbial growth is the proliferation of pathogenic microorganisms, their metabolic products and their somatic and reproductive cell parts, which contribute to the spread of disease, infection, and health disorders.
Silicon-containing quaternary ammonium salts having the following Formula I are recognized antimicrobial agents:R3N+R0nSiX4-nY−  (I)Wherein each R and each R0 is independently, a non-hydrolysable organic group; each X is, independently, a hydrolysable group; n is an integer of 0 to 3; and Y is a suitable anionic moiety to form the salt of the compound of Formula I. Such silicon containing quaternary ammonium antimicrobial agents are typically manufactured and supplied in solvents such as methanol.
The use of such silicon-containing quaternary ammonium salts in solvents adsorbed by a polymeric substrate where the quaternary salt is subsequently polymerized such that an interpenetrating network is formed within the interstices only of the polymeric substrate surface has been described in U.S. Pat. Nos. 6,146,688 and 6,572,926, the disclosures of which are hereby incorporated herein by reference. The referenced patents teach the use of the monomeric antimicrobial agents to form the interpenetrating networks in the surface pores, but make no claims as to the use of the polymeric form of the antimicrobial agents.
Despite knowledge of the common usage of silicon-containing quaternary ammonium salt monomers for imparting antimicrobial properties to solid surfaces, a method was not known for protecting surfaces through the use of polymerized silicon-containing quaternary ammonium salt polymers incorporated throughout the entire substrate or bound to the surface of the substrate. This is accomplished with the present invention.
The use of such silicon-containing quaternary ammonium compounds as antimicrobial agents in accordance with the prior art is well known and taught in a wide variety of U.S. Pat. Nos. e.g., 3,560,385; 3,794,736; 3,814,739; 5,954,869; the disclosures of which are hereby incorporated herein by reference. It is also taught that these compounds possess certain antimicrobial properties, which make them valuable and very useful for a variety of surfaces, substrates, instruments and applications (see, e.g., U.S. Pat. Nos. 3,730,701; 3,794,736; 3,860,709; 4,282,366; 4,394,378; 4,408,996; 4,414,268; 4,504,541; 4,615,937; 4,620,878; 4,631,273; 4,692,374; 4,842,766; 5,064,613; 5,358,688; 5,359,104; 5,411,585; 5,954,869; 5,959,014; 6,113,815; 6,120,587; 6,221,944; 6,469,120; 6,632,805; and 6,762,172; the disclosures of which are hereby incorporated herein by reference).
These silicon-containing quaternary ammonium antimicrobial compounds are available and widely used as disinfectants and biocides and to treat items that may undesirably support microbial growth. For example, methanol-containing, silicon-containing quaternary ammonium salts are used to treat carpeting, walls, various commercial products such as sponges and fabrics, and even water. They are also used to rehabilitate “sick buildings,” particularly after floods and water leaks, and reduce odors caused by mildew, fungi and bacterial growth in damp basement areas.
Most commercially available silicon-containing quaternary ammonium salts are generally pre-packaged in water or alcohol solutions of approximately 2 weight % to approximately 3 weight %, or less, quaternary salt concentration. They are applied to substrates, such as carpets, walls and floors, to kill the bacteria. The silicon-containing quaternary ammonium salt is often applied in a fine spray. When treating fabrics, sponges, bedding, and similar products, the concentration of the quaternary ammonium salt generally can be much lower, e.g., less than 1 weight %.
More specifically, because hospital-acquired infections are the leading cause of hospital or long-term care infections, numerous attempts have been made to create antimicrobial surfaces in hospital and medical facilities. Most treatments rely on the use of antimicrobial washes to achieve a coated surface that is resistant to bacterial growth. Unfortunately, this indiscriminate use of antimicrobial agents results in the build up of increased resistance of bacteria and certain other microorganisms to the widely used antimicrobial agents. This presents a significant problem for those being treated in health care facilities, and particularly for immune-compromised patients.
Further, some antimicrobial surface treatments use a coating treatment that provides a vehicle for entrapping the antimicrobial agent on the surface but permits subsequent diffusion of the antimicrobial agent into the biological environment. Many such treatments rely upon a leaching mechanism to deliver the antimicrobial agent into the environment.
Thus, a method has not been devised to impart to a substrate a non-leaching, biocompatible, chemically bonded antimicrobial properties throughout the entire substrate. Only the very surface has previously been made antimicrobial with a non-leaching antimicrobial agent through the formation of an interpenetrating network at the interface of the substrate surface and the antimicrobial agent, for only as deep into the surface as the antimicrobial agent could be adsorbed into the substrate. The present invention of chemically bonding or physically mixing a silicon-containing quaternary ammonium salt of Formula II (below) and a polymeric substrate, preferably in the form of a bulk resin substrate so made and methods of using such bulk resin accomplishes this goal. Thus, antimicrobial properties imparted to a material resulting from the present invention and its use are “sustained” when such material has long-lasting, non-leaching, antimicrobial properties not only on the surface, but also throughout the material, substrate, formed plastic product, device or other product made containing the antimicrobial agent of the present invention, if and when it is worked, molded, machined, abraded or otherwise formed into any desired product. As a result, whatever portion of the product made according to the present invention becomes the surface of such product after working, molding, machining, abrading or other forming or manufacturing process, the surface with which humans and animals have contact will be an antimicrobial surface. Such materials containing the antimicrobial polymer made using the present invention are not toxic to humans or animals.
There has been a long-felt need to provide durable, reliable, long-lasting, non-leaching antimicrobial substrates that exhibit effective antimicrobial characteristics throughout the substrate. Unfortunately, to date, no such substrates have been available from the industry, according to the pertinent prior art. Moreover, the antimicrobial agents described above are typically supplied in methanol. Methanol is toxic and explosive. There has long been a desire to provide the antimicrobial in a methanol-free form. The present invention satisfies these long-felt needs.
Until now, antimicrobial polymers of polymerized silicon-containing quaternary ammonium salt monomers have not been incorporated into medical polymers, thin layer films or laminates in hospitals or on medical devices and supplies to impart antimicrobial properties to such devices and supplies. The present invention accomplishes this in such a manner that does not compromise their biocompatibility.
Among other things, the present invention relates to a method for creating a solvent-free polymeric antimicrobial agent for manufacture of medical devices and supplies that is biocompatible and antimicrobial throughout the entire composition of the device or supply.
The present invention also relates to a method for creating a solvent-free polymeric antimicrobial agent for manufacture of medical devices and supplies that is biocompatible and antimicrobial on the surface of the device or supply.
The present invention also relates to a method for creating a solvent-free polymeric antimicrobial agent for manufacture of fabrics for clothing, outerwear, underwear, carpets, draperies, furniture and other articles containing fabric.
The present invention also relates to a method for creating an antimicrobial agent for liquid solutions.
The present invention additionally relates to a method for creating an antimicrobial agent for manufacture of a filter medium such as activated carbon, fiberglass, sand, fabrics and HEPA filtering materials.
The present invention also relates to a method for creating a biocompatible and solvent-free polymeric antimicrobial material for building materials, including paint thin films; and consumer products.
The present invention further relates to an antimicrobial laminate counter top that is not dependent on leaching antimicrobial agents for surface microbial protection.
The polymer of Formula II may be linear, cyclic, branched or cross-linked into three-dimensional networks.
The present invention additionally provides a method for creating a polymeric thin layer film or laminate having antimicrobial properties that can be applied to various medical and food supply surfaces.